Methods and apparatus for plasma liners with high fluid conductance

ABSTRACT

Methods and apparatus for confining plasma in a process chamber. In some embodiments, the apparatus includes a first liner with a first set of openings, the first liner configured to surround a substrate support when installed and a second liner with a second set of openings, the second liner configured to surround the substrate support under the first liner when installed, wherein the first set of openings and the second set of openings are configured to be offset from each other when installed in the process chamber to prevent a line-of-sight through the first liner and the second liner from a top down viewpoint, and wherein the first liner and the second liner are configured to be spaced apart vertically when installed in the process chamber to allow high fluid conductance through the first set of openings and the second set of openings.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. provisional patent application Ser. No. 62/722,000, filed Aug. 23, 2018 which is herein incorporated by reference in its entirety.

FIELD

Embodiments of the present principles generally relate to semiconductor processing.

BACKGROUND

Plasma is often used in semiconductor manufacturing. For example, some processes form a plasma for deposition of material on a substrate. Thus, the plasma is beneficial to the deposition process as long as the generated plasma is contained in an area where deposition is desired. If not contained, the plasma may have negative effects such as deposition on parts of the chamber itself or may cause arcing between parts of the chamber which causes pitting and other damage including defects in substrates. To prevent unwanted plasma effects, liners may be employed in a semiconductor chamber to help contain the plasma and prevent damage. One such liner may surround the substrate platform to prevent plasma from reaching the backside of the substrate. The liner is usually made from a fine mesh to control the plasma while allowing some gas flow to an exhaust pump located below the substrate. While the fine mesh liner may provide sufficient plasma control, the inventors have found that the fine mesh liner has very poor gas conductance. The poor gas conductance significantly inhibits the evacuation of gases in the semiconductor processing chamber, slowing the production rate.

Accordingly, the inventors have provided improved methods and apparatus for containing plasma in a semiconductor chamber while increasing gas conductance.

SUMMARY

Methods and apparatus for plasma liners with high fluid conductance for use in semiconductor processing are provided herein.

In some embodiments, an apparatus for confining plasma in a process may comprise a first liner with a first set of openings for fluid flow, the first liner configured to surround a substrate support of the process chamber when installed in the process chamber and a second liner with a second set of openings for fluid flow, the second liner configured to surround the substrate support of the process chamber under the first liner when installed in the process chamber, wherein the first set of openings and the second set of openings are configured to be offset from each other when installed in the process chamber to prevent a line-of-sight through the first liner and the second liner from a top down viewpoint, and wherein the first liner and the second liner are configured to be spaced apart vertically when installed in the process chamber to allow high fluid conductance through the first set of openings and the second set of openings.

In some embodiments, the apparatus may further comprise wherein the first liner or the second liner is electrically conductive, wherein the first liner or the second liner is formed form an aluminum based material, wherein the first liner or the second liner is coated with a yttrium-based material, wherein the first liner or the second liner is electrically grounded, wherein the first liner or the second liner is configured to form a symmetrical radio frequency (RF) ground return path when installed in the process chamber, wherein the first liner and the second liner are configured to be spaced apart vertically from approximately 0.25 inches to approximately 0.375 inches when installed in the process chamber, wherein a vertical distance between the first liner and the second liner is configured to be adjustable when installed in the process chamber, wherein a distance from a top surface of the first liner and a top surface of the substrate support is configured to be adjustable when the first liner is installed in the process chamber, wherein the first set of openings or the second set of openings is configured in size to prevent parasitic plasma formation when the first liner or second liner is installed in the process chamber, wherein the first liner has a first key for maintaining a first orientation when installed in the process chamber and the second liner has a second key for maintaining a second orientation when installed in the process chamber, wherein the first orientation of the first liner and the second orientation of the second liner yields an offset that provides no line-of-sight through the first liner and the second liner from a top down viewpoint when installed in the process chamber, wherein the first liner and the second liner are ohmically connected via at least one conductive gasket, and/or wherein the first liner or second liner is circular in shape with an inner cutout, wherein the first set of openings or the second set of openings, respectively, extend radially outward from an inner edge near the inner cutout towards an outer edge of the first liner or the second liner, respectively.

In some embodiments, an apparatus for confining plasma in a process chamber may comprise a first conductive liner with a first set of openings for fluid flow that is configured to surround a substrate support when installed in the process chamber, wherein the first set of openings are configured to be oriented with an offset relative to a second set of openings of a second conductive liner under the first conductive liner when installed in the process chamber.

In some embodiments, the apparatus may further comprise wherein the first conductive liner is configured to be spaced apart from the second conductive liner when installed in the process chamber, wherein the first conductive liner has a vertical inner periphery wall that is configured to be grounded to the substrate support when installed in the process chamber, and/or wherein the first conductive liner has a vertical outer periphery wall with an uppermost portion that is configured to make ohmic contact with a ground of the process chamber.

In some embodiments, an apparatus for confining plasma in a process chamber may comprise a first conductive liner with a first set of openings for fluid flow that is configured to surround a substrate support when installed in the process chamber, wherein the first set of openings are configured to be oriented with an offset relative to a second set of openings of a second conductive liner above the first conductive liner when installed in the process chamber.

In some embodiments, the apparatus may further comprise wherein the first conductive liner is configured to be spaced apart from the second conductive liner when installed in the process chamber, and/or wherein the first conductive liner has a top inner periphery edge portion that is configured to make ohmic contact with a bottom inner periphery edge portion of the second conductive liner and a top outer periphery edge portion that is configured to make ohmic contact with a bottom outer periphery edge portion of the second conductive liner when installed in the process chamber.

Other and further embodiments are disclosed below.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present principles, briefly summarized above and discussed in greater detail below, can be understood by reference to the illustrative embodiments of the principles depicted in the appended drawings. However, the appended drawings illustrate only typical embodiments of the principles and are thus not to be considered limiting of scope, for the principles may admit to other equally effective embodiments.

FIG. 1 is a cross-sectional view of a processing chamber in accordance to some embodiments of the present principles.

FIG. 2 is a cross-sectional view of a processing chamber in accordance with some embodiments of the present principles.

FIG. 3 is a cross-sectional view of a processing chamber including a substrate support with the plasma liners in accordance with some embodiments of the present principles.

FIG. 4 is a top down view of the processing chamber including the substrate support with the plasma liners in accordance with some embodiments of the present principles.

FIG. 5 is a cross-sectional view of plasma liners in accordance with some embodiments of the present principles.

FIG. 6 is a cross-sectional view a lower plasma liner with an inner liner wall and an outer liner wall in accordance with some embodiments of the present principles.

FIG. 7 is a cross-sectional view of an upper plasma liner with an inner liner wall and an outer liner wall in accordance with some embodiments of the present principles.

FIG. 8 is a cross-sectional view of an upper plasma liner with an inner liner wall and an outer liner wall in accordance with some embodiments of the present principles.

FIG. 9 is a cross-sectional view of an upper plasma liner and a lower plasma liner in accordance to some embodiments of the present principles.

To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. The figures are not drawn to scale and may be simplified for clarity. Elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.

DETAILED DESCRIPTION

The methods and apparatus provide a chamber liner for containing plasma in a semiconductor process chamber that has high fluid conductance and provides a uniform RF return path between the chamber liner and chamber ground. The chamber liner provides a continuous conductive boundary for RF currents in plasma to return back to the source and also incorporates, at the same time, symmetrical non-line-of-sight multiple pumping slots or openings. The non-line-of-sight pumping slots are achieved by a staggered, two plane structure at different heights with each layer having pump slots that are offset from pump slots in the other layer. From a top down vantage point, the plasma boundary provided by the chamber liner appears as a continuous liner. Unlike a traditional approach that uses a fine metal grid with hole sizes selected to confine the plasma, the chamber liner according to the present principles does not inhibit fluid conductance and may provide approximately 40 percent to approximately 50 percent or more increased fluid conductance over traditional approaches.

In some embodiments of the present principles, the two plane, staggered approach provides an equipotential continuous metal structure for plasma RF currents to return while providing high gas conductance for evacuating the process chamber quickly, improving throughput and reducing costs. Large, symmetrical pumping slots in each plane allow high gas conductance while the staggered relationship of the pumping slots in each plane provide no direct line-of-sight to the plasma to minimize unpredictable parasitic plasma ignition. The inventors have found that with traditional approaches, images of the pumping ports of a process chamber may be found on wafers after processing. The images are caused by the highly restrictive screens of traditional approaches that inhibit gas flow except for high vacuum areas directly above the pumping ports. The non-uniform flow pattern caused by the restrictive screens affects the processing of the wafer near the pumping port locations. By using embodiments of the present principles, uniform flow conductance is maintained and wafer processing issues caused by the pumping port locations are minimized or eliminated altogether.

FIG. 1 is a cross-sectional view of a process chamber 100 that illustrates the operation of an upper plasma liner 120 and a lower plasma liner 122 when installed according to the present principles. The process chamber 100 includes a pump 102 for exhausting gases from the process chamber 100 and a substrate support 104. The substrate support 104 includes an electrode 106 that is connected to an RF power source 110 via a match network 108. Openings 120A in the upper plasma liner 120 are offset from openings 122A in the lower plasma liner 122. The offsetting of the openings 122A, 120A prohibits a direct line of sight 130 from occurring in a top down viewpoint from inside the process chamber 100 where plasma 124 is formed, containing the plasma 124. Because the upper plasma liner 120 and the lower plasma liner 122 are vertically spaced apart, gases in the process chamber 100 can flow 132 through the upper plasma liner 120 and the lower plasma liner 122 with high fluid conductance. The high fluid conductance dramatically reduces pressure deltas between areas above the plasma liners 120, 122 such as the processing volume of the process chamber 100 and areas below the plasma liners 120, 122 such as areas near the pump exhaust ports. In addition, the upper plasma liner 120 and the lower plasma liner 122 provide a symmetrical high conductance ground return path for RF current 126.

FIG. 2 is a cross sectional view of a process chamber 200 in which embodiments of the present principles may be implemented. As shown, the process chamber 200 is an etch chamber suitable for etching a substrate, such as substrate 201. Examples of process chambers which benefit from aspects described herein are available from Applied Materials, Inc., located in Santa Clara, Calif. Other process chambers, including those from other manufacturers, may be adapted to benefit from aspects of the disclosure. In some embodiments, the process chamber 200 includes a chamber body 202, a gas distribution plate assembly 204, and a substrate support 206. The chamber body 202 of the process chamber 200 includes or may be formed from one or more process-compatible materials, such as aluminum, anodized aluminum, nickel plated aluminum, nickel plated aluminum 6061-T6, stainless steel, as well as combinations and alloys thereof, for example. The substrate support 206 functions as an electrode in conjunction with the gas distribution plate assembly 204. As such, a plasma may be formed in a processing volume 208 defined between the gas distribution plate assembly 204 and an upper surface of the substrate support 206. The substrate support 206 includes or is formed of a conductive material, such as aluminum, a ceramic material, or a combination of both. The chamber body 202 is also coupled to a vacuum system 210 that includes a pump and a valve, and a liner 212 may be disposed on surfaces of the chamber body 202 in the processing volume 208. The chamber body 202 includes a port 214 formed in a sidewall thereof. The port 214 is selectively opened and closed to allow access to the interior of the chamber body 202 by a substrate handling robot (not shown). In such an embodiment, a substrate 201 is transferred in and out of the process chamber 200 through the port 214. The substrate 201 is positioned on the upper surface 216 of the substrate support 206 for processing. Lift pins (not shown) may be used to space the substrate 201 away from the upper surface of the substrate support 206, such as to enable exchange with the substrate handling robot during substrate transfer.

The gas distribution plate assembly 204 is positioned on the chamber body 202. A power source 211, such as a radio frequency (RF) power source, is coupled to gas distribution plate assembly 204 to electrically bias the gas distribution plate assembly 204 relative to the substrate support 206 to facilitate plasma generation within the process chamber 200. The substrate support 206 includes an electrostatic chuck 218, in which the electrostatic chuck 218 may be connected to a power source 209 a to facilitate chucking of the substrate 201 and/or to influence a plasma located within the processing volume 208. The power source 209 a includes a power supply, such as a DC or RF power supply, and is connected to one or more electrodes 220 of the electrostatic chuck 218. A bias source 209 a may additionally or alternatively be coupled with the substrate support 206 to assist with plasma generation and/or control, such as to an edge ring assembly. The bias source 209 b may illustratively be a source of up to about 1000 W (but not limited to about 1000 W) of RF energy at a frequency of, for example, approximately 13.56 MHz, although other frequencies and powers may be provided as desired for particular applications. The bias source 209 b is capable of producing either or both of continuous or pulsed power. In some aspects, the bias source may be capable of providing multiple frequencies, such as 13.56 MHz and 2 MHz.

The process chamber 200 may also include a controller 295. The controller 295 includes a programmable central processing unit (CPU) 296 that is operable with a memory 297 and a mass storage device, an input control unit, and a display unit (not shown), such as power supplies, clocks, cache, input/output (I/O) circuits, and the liner, coupled to the various components of the processing system to facilitate control of the substrate processing. To facilitate control of the process chamber 200 described above, the CPU 296 may be one of any form of general purpose computer processor that can be used in an industrial setting, such as a programmable logic controller (PLC), for controlling various chambers and sub-processors. The memory 297 is coupled to the CPU 296 and the memory 297 is non-transitory and may be one or more of random access memory (RAM), read only memory (ROM), floppy disk drive, hard disk, or any other form of digital storage, local or remote. Support circuits 298 are coupled to the CPU 296 for supporting the processor. Applications or programs for charged species generation, heating, and other processes are generally stored in the memory 297, typically as software routine. The software routine may also be stored and/or executed by a second CPU (not shown) that is remotely located from the process chamber 200 being controlled by the CPU 296.

The memory 297 is in the form of computer-readable storage media that contains instructions, when executed by the CPU 296, to facilitate the operation of the process chamber 200. The instructions in the memory 297 are in the form of a program product such as a program that implements the method of the present disclosure. The program code may conform to any one of a number of different programming languages. In one example, the disclosure may be implemented as a program product stored on a computer-readable storage media for use with a computer system. The program(s) of the program product define functions of the aspects (including the methods described herein). Illustrative computer-readable storage media include, but are not limited to: non-writable storage media (e.g., read-only memory devices within a computer such as CD-ROM disks readable by a CD-ROM drive, flash memory, ROM chips, or any type of solid-state non-volatile semiconductor memory) on which information is permanently stored; and writable storage media (e.g., floppy disks within a diskette drive or hard-disk drive or any type of solid-state random access semiconductor memory) on which alterable information is stored. Such computer-readable storage media, when carrying computer-readable instructions that direct the functions of the methods described herein, are aspects of the present principles.

FIG. 3 is a cross-sectional view of a process chamber 300 including a substrate support 306 with the plasma liners 310A, 310B in accordance with some embodiments. FIG. 4 is a top down view of the process chamber 300 including the substrate support 306 with the plasma liners 310A, 310B in accordance with some embodiments. FIG. 5 is a cross-sectional view of the plasma liners 310A, 310B in accordance with some embodiments. The process chamber 300 includes a chamber body 302 with the substrate support 306 positioned within the chamber body 302. In some embodiments, the plasma liners 310A, 310B extend radially outward from the substrate support 306, such as by being positioned about and encircling the substrate support 306 within the chamber body 302. In some embodiments, one or more of the plasma liners 310A, 310B may be made of aluminum or the like.

The plasma liners 310A, 310B include an upper plasma liner 310A and a lower plasma liner 310B positioned under the upper plasma liner 310A. The upper plasma liner 310A includes one or more openings 312A formed therethrough, and the lower plasma liner 310B correspondingly includes one or more openings 312B formed therethrough. The plasma liners 310A, 310B are positioned about the substrate support 306 such that the openings 312A of the upper plasma liner 310A are rotationally offset from the openings 312B of the lower plasma liner 310B, such as with respect to an axis of the substrate support 306. For example, as shown specifically in FIG. 3, a line of sight is obstructed or prevented through the upper plasma liner 310A and the lower plasma liner 310B by having the openings 312A of the upper plasma liner 310A rotationally offset from the openings 312B of the lower plasma liner 310B. The line of sight provided through the openings 312A of the upper plasma liner 310A is obstructed or prevented by the lower plasma liner 310B, as the openings 312B of the lower plasma liner 310B do not rotationally overlap with the openings 312A of the upper plasma liner 310A. In some embodiments, the upper plasma liner 310A and/or the lower plasma liner 3106 may be keyed to preserve the orientation between the upper plasma liner 310A and the lower plasma liner 310B when installed in the process chamber 300. The openings 312A, 312B are sized to reduce or eliminate parasitic plasma from occurring in the openings 312A, 312B while still providing high fluid conductance. If the openings 312A, 312B are too large, high fluid conductance may be achieved but parasitic plasma may form. In some embodiments, the size of the openings 312A, 312B may be adjusted based on process chamber parameters (e.g., size of processing volume, RF frequency range, RF power range, generated field orientation, etc.) and/or processing parameters (e.g., RF frequency, RF power, etc.).

In some embodiments, the openings 312A of the upper plasma liner 310A may be the same number as the openings 312B of the lower plasma liner 310B. In some embodiments, the openings 312A of the upper plasma liner 310A may be the same size and/or shape as the openings 312B of the lower plasma liner 310B. In some embodiments, the upper plasma liner 310A may be identical to the lower plasma liner 310B. In some embodiments, the upper plasma liner 310A may also be rotationally offset from the lower plasma liner 310B by approximately one degree, approximately five degrees, or more. For example, in the embodiments shown in FIGS. 3, 4, and 5, the upper plasma liner 310A and the lower plasma liner 310B may each include thirty-six openings 312A, 312B. In such embodiments, the upper plasma liner 310A may be rotationally offset from the lower plasma liner 310B by approximately five degrees. If fewer openings 312A and 312B are included within the upper plasma liner 310A and the lower plasma liner 310B, the upper plasma liner 310A may be rotationally offset from the lower plasma liner 310B by more than approximately five degrees. If more openings 312A and 312B are included within the upper plasma liner 310A and the lower plasma liner 310B, the upper plasma liner 310A may be rotationally offset from the lower plasma liner 310B by less than approximately five degrees.

In some embodiments, the upper plasma liner 310A and/or the lower plasma liner 310B may be integrally formed with the substrate support 306, or may be formed separately from and one or more of the plasma liners 310A, 310B may be coupled to the substrate support 306. In some embodiments in which one or both of the upper plasma liner 310A and the lower plasma liner 310B are formed separate from the substrate support 306, one or more spacers 314 may be positioned between the upper plasma liner 310A and the lower plasma liner 310B. The spacers 314 may facilitate spacing and positioning between the upper plasma liner 310A and the lower plasma liner 310B. In some embodiments, the spacers 314 may incorporated directly into the upper plasma liner 310A and/or the lower plasma liner 3106 and may include a recess for an RF gasket (RF conductive material) and the like. In some embodiments, the spacers 314 may be located near an inner periphery of the upper plasma liner 310A and the lower plasma liner 310B and/or may be located near an outer periphery of the upper plasma liner 310A and the lower plasma liner 3106.

FIG. 6 depicts a lower plasma liner 602 with an inner liner wall 606 and an outer liner wall 608. The upper plasma liner 604 is above the lower plasma liner 602 and makes ohmic contact with the inner liner wall 606 and the outer liner wall 608 on an inner peripheral edge 612 of the upper plasma liner 604 and an outer peripheral edge 614 of the upper plasma liner 604, respectively. The inner liner wall 606 of the lower plasma liner 602 makes ohmic contact with a substrate support 610. In some embodiments, a top edge 616 of the outer liner wall 608 may make ohmic contact with another process chamber assembly that extends to or near a top of the process chamber (see, e.g., FIG. 7). RF current may then flow from the process chamber through the lower plasma liner 602 and the upper plasma liner 604 to the substrate support 610, providing an equidistant ground return path for the RF current.

FIG. 7 depicts an upper plasma liner 702 with an inner liner wall 706 and an outer liner wall 708. The lower plasma liner 704 is below the upper plasma liner 702 and makes ohmic contact with the inner liner wall 706 and the outer liner wall 708 on an inner peripheral edge 712 of the lower plasma liner 704 and an outer peripheral edge 714 of the lower plasma liner 704, respectively. The inner liner wall 706 of the upper plasma liner 702 makes ohmic contact with a substrate support 710. In some embodiments, a top edge 716 of the outer liner wall 708 may make ohmic contact with another process chamber assembly 718 that extends to or near a top of the process chamber. RF current may then flow from the process chamber through the upper plasma liner 702 and the lower plasma liner 704 to the substrate support 710, providing an equidistant ground return path for the RF current.

FIG. 8 is a cross-sectional view of an upper plasma liner 802 with a vertical inner liner wall 806 and a vertical outer liner wall 808 in accordance with some embodiments. The lower plasma liner 804 is below the upper plasma liner 802 and makes ohmic contact with the inner liner wall 806 and the outer liner wall 808 on an inner peripheral edge 812 of the lower plasma liner 804 and an outer peripheral edge 814 of the lower plasma liner 804, respectively. In some embodiments, the inner peripheral edge 812 of the lower plasma liner 804 may have an inner portion 818 that extends upward and has a recess that holds a first RF gasket 820. The first RF gasket 820 mates with the upper plasma liner 802 to provide ohmic contact between the upper plasma liner 802 and the lower plasma liner 804. In some embodiments, the outer peripheral edge 814 of the lower plasma liner 804 may have an outer portion 822 that extends upward and has a recess that holds a second RF gasket 824. The second RF gasket 824 mates with the upper plasma liner 802 to provide ohmic contact between the upper plasma liner 802 and the lower plasma liner 804.

In some embodiments, the outer liner wall 808 of the upper plasma liner 802 may only make ohmic contact with other process chamber assemblies (not shown) at an upper portion 816 of the outer liner wall 808. In some embodiments, the upper plasma liner 802 may have a recess 826 formed in the upper portion 816 of the outer liner wall 808 that holds a third RF gasket 828. The third RF gasket mates with another assembly (not shown, see FIG. 7) to provide ohmic contact between the upper plasma liner 802 and another assembly. The inner liner wall 806 of the upper plasma liner 802 makes ohmic contact with a substrate support (not shown, see FIGS. 1-7). RF current may then flow from the process chamber through the upper plasma liner 802 and the lower plasma liner 804 to the substrate support, providing an equidistant ground return path for the RF current. In some embodiments, an upper portion 830 of the inner liner wall 806 of the upper plasma liner 802 includes a flange 832 that provides ohmic contact with the substrate support (not shown). In some embodiments, the upper plasma liner 802 and/or the lower plasma liner 804 may be coated and/or anodized to protect against plasma damage and/or corrosion. The coating may include yttrium-based coatings and the like. In some embodiments, the yttrium-based coating may be approximately 10 mils thick. In some embodiments, the RF gaskets 820, 824, 828 may be made of a stainless steel based material or a beryllium-copper based material and the like. In some embodiments, the RF gaskets 820, 824, 828 may have a structure with a solid center and/or may have a structure with a hollow center for easier compression when installed.

FIG. 9 is a cross-sectional view of an upper plasma liner 904 and a lower plasma liner 902 according to some embodiments. A first distance 906 between the upper plasma liner 904 and the lower plasma liner 902 allows gas flow (conductance) 920 through the upper plasma liner 904 and the lower plasma liner 902 without providing significant restriction while still inhibiting direct line-of-sight for plasma generated above the upper plasma liner. In some embodiments, the first distance 906 may be from approximately 0.25 inches to approximately 0.375 inches. In some embodiments, the first distance 906 between the upper plasma liner 904 and the lower plasma liner 902 may be manually and/or automatically adjusted by an actuator 914 that is connected via an actuator assembly 916 to the upper plasma liner 904 and/or the lower plasma liner 902. The first distance 906 may then be adjusted for different processes in the process chamber. In some embodiments, the first distance 906 may be adjusted to increase or decrease gas conductance or to completely stop (seal) the flow of gas (e.g., bringing the lower plasma liner 902 into contact with the upper plasma liner and vice versa). The controller 295 of FIG. 2 may be used to automatically adjust the first distance 906 via the actuator 914 based upon the process parameters and/or chamber parameters and the like to ensure substrate edge uniformity. In some embodiments, the upper plasma liner 904 or the lower plasma liner 902 may be integrated with a movable substrate support and may move with the movable substrate support while the other liner is stationary to control the first distance 906.

A second distance 908 from an upper surface 918 of the upper plasma liner 904 to an upper surface 912 of a substrate support 910 may be adjusted to compensate for edge uniformity effects of the plasma generated above the upper plasma liner 904. The second distance 908 may be varied based upon RF frequency and/or RF power levels used to generate the plasma. In some embodiments, the second distance is approximately two inches. In some embodiments, the upper plasma liner 904 and the lower plasma liner 902 may be adjusted to facilitate in differences in operating parameters of a given process chamber. In some embodiments, the upper plasma liner 904 and the lower plasma liner 902 may be manually and/or automatically adjusted up or down (arrow 924) by an actuator 914 that is connected via an actuator assembly 916 to the upper plasma liner 904 and/or the lower plasma liner 902. The second distance 908 may then be adjusted for different processes in the process chamber. The controller 295 of FIG. 2 may be used to automatically adjust the second distance 908 via the actuator 914 based upon the process parameters and/or chamber parameters and the like to ensure substrate edge uniformity. In some embodiments, the upper plasma liner 904 and the lower plasma liner 902 may be held stationary while a movable substrate support may move the upper surface 912 upwards and downwards (arrow 922) to control the second distance 908.

Embodiments in accordance with the present principles may be implemented in hardware, firmware, software, or any combination thereof. Embodiments may also be implemented as instructions stored using one or more computer readable media, which may be read and executed by one or more processors. A computer readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing platform or a “virtual machine” running on one or more computing platforms). For example, a computer readable medium may include any suitable form of volatile or non-volatile memory. In some embodiments, the computer readable media may include a non-transitory computer readable medium.

While the foregoing is directed to embodiments of the present principles, other and further embodiments of the principles may be devised without departing from the basic scope thereof. 

1. An apparatus for confining plasma in a process chamber, comprising: a first liner with a first set of openings for fluid flow, the first liner configured to surround a substrate support of the process chamber when installed in the process chamber; and a second liner with a second set of openings for fluid flow, the second liner configured to surround the substrate support of the process chamber under the first liner when installed in the process chamber, wherein the first set of openings and the second set of openings are configured to be offset from each other when installed in the process chamber to prevent a line-of-sight through the first liner and the second liner from a top down viewpoint, and wherein the first liner and the second liner are configured to be spaced apart vertically when installed in the process chamber to allow high fluid conductance through the first set of openings and the second set of openings.
 2. The apparatus of claim 1, wherein the first liner or the second liner is electrically conductive.
 3. The apparatus of claim 2, wherein the first liner or the second liner is formed form an aluminum based material.
 4. The apparatus of claim 3, wherein the first liner or the second liner is coated with a yttrium-based material.
 5. The apparatus of claim 2, wherein the first liner or the second liner is electrically grounded.
 6. The apparatus of claim 5, wherein the first liner or the second liner is configured to form a symmetrical radio frequency (RF) ground return path when installed in the process chamber.
 7. The apparatus of claim 1, wherein the first liner and the second liner are configured to be spaced apart vertically from approximately 0.25 inches to approximately 0.375 inches when installed in the process chamber.
 8. The apparatus of claim 1, wherein a vertical distance between the first liner and the second liner is configured to be adjustable when installed in the process chamber.
 9. The apparatus of claim 1, wherein a distance from a top surface of the first liner and a top surface of the substrate support is configured to be adjustable when the first liner is installed in the process chamber.
 10. The apparatus of claim 1, wherein the first set of openings or the second set of openings is configured in size to prevent parasitic plasma formation when the first liner or second liner is installed in the process chamber.
 11. The apparatus of claim 1, wherein the first liner has a first key for maintaining a first orientation when installed in the process chamber and the second liner has a second key for maintaining a second orientation when installed in the process chamber, wherein the first orientation of the first liner and the second orientation of the second liner yields an offset that provides no line-of-sight through the first liner and the second liner from a top down viewpoint when installed in the process chamber.
 12. The apparatus of claim 1, wherein the first liner and the second liner are ohmically connected via at least one conductive gasket.
 13. The apparatus of claim 1, wherein the first liner or second liner is circular in shape with an inner cutout, wherein the first set of openings or the second set of openings, respectively, extend radially outward from an inner edge near the inner cutout towards an outer edge of the first liner or the second liner, respectively.
 14. An apparatus for confining plasma in a process chamber, comprising: a first conductive liner with a first set of openings for fluid flow that is configured to surround a substrate support when installed in the process chamber, wherein the first set of openings are configured to be oriented with an offset relative to a second set of openings of a second conductive liner under the first conductive liner when installed in the process chamber.
 15. The apparatus of claim 14, wherein the first conductive liner is configured to be spaced apart from the second conductive liner when installed in the process chamber.
 16. The apparatus of claim 14, wherein the first conductive liner has a vertical inner periphery wall that is configured to be grounded to the substrate support when installed in the process chamber.
 17. The apparatus of claim 14, wherein the first conductive liner has a vertical outer periphery wall with an uppermost portion that is configured to make ohmic contact with a ground of the process chamber.
 18. An apparatus for confining plasma in a process chamber, comprising: a first conductive liner with a first set of openings for fluid flow that is configured to surround a substrate support when installed in the process chamber, wherein the first set of openings are configured to be oriented with an offset relative to a second set of openings of a second conductive liner above the first conductive liner when installed in the process chamber.
 19. The apparatus of claim 18, wherein the first conductive liner is configured to be spaced apart from the second conductive liner when installed in the process chamber.
 20. The apparatus of claim 18, wherein the first conductive liner has a top inner periphery edge portion that is configured to make ohmic contact with a bottom inner periphery edge portion of the second conductive liner and a top outer periphery edge portion that is configured to make ohmic contact with a bottom outer periphery edge portion of the second conductive liner when installed in the process chamber. 